In a corrugating machine intended for the manufacture of single-face corrugated cardboard, for example of the type described in French Pat. No. 2,433,985, the web of corrugating paper is corrugated by passing between two grooved cylinders and glued to a web of cover paper between the lower grooved cylinder located downstream and a smooth cylinder around which the cover paper passes.
The glue is deposited on the summits of the corrugations of the corrugating paper with the aid of a gluing cylinder driven in a rotary movement and dipping into a tank of glue. The width of the gluing zone, i.e., the zone of the cylinder wetted by the glue, is conventionally dictated, as described in detail in the above-mentioned French patent, by the adjustable distance between two barriers, both of which are movable in the glue tank.
If the gluing zone is narrower than the width of the web of corrugating paper, wastage occurs through lack of glue on the edges.
If the gluing zone is wider than the width of the web of corrugating paper, the excess glue is then deposited on the lower grooved cylinder, thus soiling it and entailing stoppages of the machine for cleaning purposes. These two problems have become crucial because of the generalized use of reel launchers which now make it possible for the end of one reel to be connected practically end to end to the beginning of the next reel. When the two reels are of the same width, the gluing zone remains the same and there is no difficulty. However, the hazards of manufacturing programs often have the consequence that the widths of successive reels are not the same, and it is then necessary to change the position of the barriers, in order to ensure that the gluing zone corresponds to the new width of paper being processed. This movement takes a certain time, and, as the change of width of the paper is instantaneous, either wastage is then caused through lack of glue or the lower grooved cylinder is soiled.
At the present time this problem is solved by completely shutting down the machine during the movement of the barriers in the glue tank. This obviously entails a not inconsiderable loss of production.